1. Field of the Invention
The present invention relates to a charge trap type non-volatile memory device and a method for manufacturing the charge trap type non-volatile memory device.
2. Background Art
A charge trap type non-volatile memory device is known as a kind of non-volatile memory devices capable of electrically writing, reading and erasing data (for example, Japanese Patent Laid-Open No. 2007-142468). This charge trap type non-volatile memory device has a plurality of memory cells and performs the writing of data by causing electric charges to be trapped in charge films (silicon nitride films).
In recent years, miniaturization has gone ahead in charge trap type non-volatile memory devices, and as a result of this, memory cells adjacent to each other come closer to each other than before, with the result that the mutual interference of memory cells has become great. If the mutual interference becomes great, it becomes difficult to obtain memory cells having good writing and reading characteristics.
Therefore, it is necessary to more positively reduce the mutual interference of memory cells.
In a charge trap type non-volatile memory device, in the case of formation of a shallow trench isolation (STI) structure that performs element isolation by burying a trench insulating film between a pair of memory cells adjacent to each other, it is effective to lower the height of the buried insulating film in order to reduce the mutual interference of the adjacent memory cells. The reason for this is that because the capacitance between the adjacent memory cells can be reduced by lowering the height of the above-described buried insulating film, this leads to a reduction in the mutual interference of the adjacent memory cells.